Gas turbines operate under extreme conditions, including elevated temperatures under corrosive environments. As the operating temperatures of gas turbines increase to achieve improved efficiency, advanced materials, such as nickel-based superalloys, have been utilized for various turbine components, particularly in the hot gas path. For some alloys and usages, including certain critical hot gas path components, nickel-based superalloys having a single-crystal grain structure have desirable properties, which may include mechanical properties which are superior to other available materials.
However, nickel-based superalloys may be susceptible to stress accelerated gamma prime oxidation (SAGPO) static crack growth. SAGPO static crack growth may occur when a crack tip is internally and preferentially oxidized under operating conditions of a gas turbine. Elevated susceptibility of SAGPO static crack propagation may be present in nickel-based superalloys having a single-crystal grain structure. Indeed, this susceptibility may in certain cases be so severe that turbine components formed from advanced single crystal nickel-based superalloys can fracture under operating conditions. In particular, the single-crystal nickel-based superalloys may have heightened susceptibility to SAGPO static crack growth when the alloy is located in a portion of a turbine component which is subjected to temperatures below the typical operating profile for the alloy, such as, for example, at a temperature of less than about 1,100° F.